1. Technical Field
The present invention relates to a recording tape cartridge that accommodates inside a case a recording tape, such as a magnetic tape, mainly used as a recording and playback medium in computers or the like, and to a drive device into which the recording tape cartridge is loaded.
2. Related Art
Recording tape cartridges in which a recording tape, such as a magnetic tape or the like, is wound on a reel (reel hub) and the single reel is accommodated within a case are conventionally known. The recording tape cartridge is used as a data recording/playback medium of computers or the like. When the recording tape cartridge is loaded into a drive device, the recording tape is pulled-out from an opening via a leader member. The recording tape which is pulled-out is taken-up onto a take-up reel which is disposed at the opposite side of the recording tape cartridge, with tape guides and a recording/playback head of the drive device therebetween.
Recording/playback systems (drive devices), which use recent recording tape cartridges which have improved recording density, are mainly of a type in which, on the basis of servo signals which are recorded in advance on the recording tape, the recording/playback head is moved in the vertical direction by an actuator with making the recording/playback head follows the servo signals, and data signals are recorded. Accordingly, it is desirable that the recording tape, which has been pulled-out from the recording tape cartridge, is supported by a plurality of tape guides within the drive device, and that control is carried out so that the recording tape always travels past a predetermined position of the recording/playback head.
Examples of tape guiding systems within a drive device are: a system in which a cylindrical-shaped member rotates and regulating portions (flanges) are formed at both ends of the member, a system in which a similar cylindrical-tube-shaped member or a block-shaped member is disposed so as to be fixed disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2004-362755; a system in which a block-shaped member, which jets-out air and actively causes the recording tape to rise up, is disposed so as to be fixed disclosed in Japanese National Publication No. 9-511352, and the like.
It is difficult to provide the reel within the recording tape cartridge and the reel hub of the take-up reel within the drive device to be straight absolutely. It is also difficult to straightly assemble and operate the tape guides and motors which rotate the respective reels. Therefore, even if the recording tape is supported by the tape guides of the drive device, the recording tape fluctuates in the transverse direction (the vertical direction) while traveling.
In cases in which these fluctuations are marked, and, in particular, in cases in which the recording tape fluctuates in a short time period (large acceleration), it may be difficult for the recording/playback head, which moves in the vertical direction on the basis of the servo signals on the recording tape, to record or play-back the data signals because of these sudden positional fluctuations of the recording tape.
Further, in recent recording/playback systems having high recording density, the size of the servo signals is made to be small, the recording density of the servo signals themselves is increased, and the traveling speed of the recording tape is made to be faster. Therefore, recording/playback errors of the data signals arising due to reading errors of the servo signals may happen because of the recording tape fluctuation of a level which has not been problematic conventionally.
There are various factors causing fluctuations of the recording tape, such as bending of the recording tape, dispersion in the thickness distribution, residual warping, curling, an irregular curl in the transverse direction (heightwise direction) at the time when the recording tape is taken-up, the degrees of straightness of the take-up reel and the reel of the tape cartridge, the degrees of straightness of the motor, the tape guides, and the recording/playback head of the drive device, tape tension, positional offset in the transverse direction (vertical direction) of the plural tape guides, sliding resistance between the recording tape and contacting members, and the like.
If the traveling position of the recording tape becomes unstable for any reason, this becomes a cause of the winding position of the recording tape being in disorder when the recording tape is taken-up onto the reel or the take-up reel, and, when the recording tape is next fed-out in the opposite direction, fluctuations in the position of the recording tape arising, or the recording tape colliding with the regulating portions (flanges) of the cylindrical-tube-shaped tape guides such that the transverse direction end portions (edges) thereof become damaged.
Moreover, low-cost members are required in recording tape cartridges which are mass produced and consumed, as compared with the number of drive devices. Therefore, it is difficult to supply a recording tape cartridge which is adjusted at the time of assembly such that the precision thereof is improved. Further, as compared with the tape guides of the drive device, the dimensions of the reel hub of the tape cartridge are relatively large. Therefore, it is also difficult to obtain a reel hub having a cylindrical-tube shape which is as highly accurate as the tape guides of the drive device.
Further, when the recording tape is wound so as to be off-center with respect to the center position in a transverse direction (height direction) of the reel hub and skewed toward one or other of the upper and lower flanges, the state of winding (wound surface which faces the flange) of the recording tape is in good order (is flat) (referred to below as “order winding”). However, with this kind of winding, there have been cases where a phenomenon (referred to below as a “one wind flying phenomenon”) has occurred where one wind of the recording tape flies out in a transverse direction from the orderly wound surface at an end portion in a transverse direction.
When the one wind flying phenomenon occurs, the end portion in a transverse direction of the one wind that has flown out can become kinked through contact with the upper flange or the lower flange when the recording tape cartridge is impacted during transportation or when dropped, for example, and when the recording tape is run inside the drive device, there have been problems such as reading errors of servo signals occurring or it becoming impossible to record or playback information.
In contrast, when the recording tape is wound at the substantial center in a transverse direction of the reel hub, the wound surface is not ordered and becomes a moderately and continuously convex and concave shaped (irregular-shaped) wound surface (referred to below as “coarse winding”). Hitherto, coarse winding has been avoided due to instability in a transverse direction (vertical movement) when the recording tape is traveling and the unfavorable external appearance of the shape; however, it has been understood that the amount of flying out of one wind (the difference in the amount of flying out of adjacent winds of the recording tape) at coarse winding is less than the amount of flying out in the case of the one wind flying phenomenon that occurs with order winding.
In other words, it has been understood that with coarse winding, it is more difficult for the transverse direction end portions of the recording tape to be damaged when an impact is received during transportation or when dropped, for example, and even damage received is minimal. Further, while depending on the extent of the coarse winding, it has become clear that vertical movement of the recording tape when traveling can be maintained within an allowable range. Accordingly, it is preferable for winding to be conducted such that the transverse direction center position of the recording tape comes to the substantial transverse direction (height direction) center position of the reel hub.